While devices for imparting a false twist to a yarn abound in the art, a particular interest can be found in a false-twist device of the type described in German Pat. No. 2,628,396. In this false-twist device, a pair of endless belts or bands are oriented so that respective passes or stretches of the belt cross one another, preferably at right angles, the yarn being fed to the crossing point so as to include angles of 45.degree. with both of the belts.
The two belts can lie in respective mutually intersecting planes and the yarn can pass perpendicularly through the line at which the planes intersect.
The belts may be driven at the same or different speeds and impart, as described in that publication, a false twist to the yarn.
One of the problems encountered with this system, however, is the need to provide means for pressing the yarn and contacting surfaces of the belts toward one another uniformly.
For this purpose, in practice, pressing plates or other members have been required.
However, in an operation of conventional false-twist devices of this type, vibrations in the yarn-contacting pass or stretch frequently cause the belts to slap together and hit the yarn in a fluctuating manner, to the detriment of uniform operation.
With the conventional systems, therefore, it was difficult, it not impossible, to ensure a constant pressure of the belts against the yarn.